This invention relates generally to visual signalling and particularly to the regulation of vehicular and/or pedestrian traffic under power failure conditions. More specifically, this invention is directed to a signalling device which operates in cooperation with an electrically controlled indicator, for example a traffic signal, for displaying a command signal upon the occurrence of a condition, power failure for example, to which the signalling device is responsive.
While not limited thereto in its utility, the present invention is particularly well suited for use in combination with conventional electrically powered traffic signals. It has long been recognized that public reliance on traffic signals can result in unfortunate consequences when the traffic signal is rendered inoperative due to an electrical power outage. The potential for a safety hazard is particularly acute at controlled relatively high-speed traffic intersections. A number of devices, operable in cooperation with a traffic signal, have been proposed for presenting a warning signal under certain conditions. Such prior warning devices are relatively complicated and difficult to install and may require extensive modification of the traffic signal.
In U.S. Pat. No. 3,863,214, entitled "Supplemental Visual Display for Traffic Signal", a visual display supplements a unidirectional traffic signal. During power disruption, the supplemental visual display indicates that the traffic signal is inoperative. The supplemental display includes an arm which supports a warning device at one end thereof. The arm is raised by an electric motor in response to an electric signal from the traffic signal controller. The arm is normally retained in an upright position by an electromagnet. In the event of a power outage, the electromagnet is released and the arm pivots to indicate that the traffic signal is inoperative. The arm is coupled to a shaft of a motor which returns the arm to the upright position when the power is restored.
The present invention is a power failure responsive warning device of modular form which does not require either an electric motor or a complex switching circuit and which may be easily mounted or fixed to a multi-directional traffic signal or the like.